Rail bond and method of making the same



1943- E. SABOL 2,333,046

RAIL BOND AND METHOD OF MAKING THE SAME Filed NOV. 8, 1939 Patented Oct.26, 1943 RAIL BOND AND METHOD OF MAKING THE SAME Ernest J. Sabol,Worcester, Mesa, assignor to The American Steel and Wire Company of NewJersey, a corporation of New Jersey Application November 8, 1939, SerialNo. 303,485

Claims.

This invention is concerned with rail bonds having the conductor strandsmechanically joined to the terminals, the primary object being toprovide joints of high electrical conductivity and strength between theconductor strands and terminals in a manner permitting quantityproduction of the bonds.

Specific examples of the invention are illustrated by the accompanyingdrawing in which:

Figure 1 is a side view of an electric power bond of the type whereinthe conductor strand spans the outside of the rail joint splice bar;

Figure 2 is an enlargement from Figure 1 showing the Joint in section;

Figure 3 is a cross section taken from the line III-III of Figure 1;

Figure 4 is a longitudinal section showing a partially completed Jointbetween the terminal and conductor strand as applied to a bond of thetype wherein the conductor strand passes between the rail bond splicebar and the rail web? Figure 5 is the same as Figure 4 excepting thatthe Joint is completed;

Figures 6, 7 and 8 are sections taken from the lines VI-VI, VII-VII andVIII-VIII, respectiveiy, in Figure 5: and

Figures 9 and 10 show the preparation of the terminal and conductorstrand end, respectively, to condition them for Joining- Morespecifically the bond illustrated by Figtires 1 through 3 comprises aterminal having a head i, a solid stud I and a tubular shank 8, the

end of the conductor strand I being inserted in the tubular shank 3 andthe latter being cold compressed so as to iorm a ioint between theterminal and conductor strand.

The terminal is a solid integral forging of pure electrolytic copper,the shank 3 being rendered tubular by drilling which normally leaves asmooth cylindrical inside. The conductor strand 4 i made of intertwistedcold drawn copper wires.

It follows from the above that when the end of the conductor strand isinserted in the inside of the tubular shank, the interengI-sing surfacesare smoothfthe inside of the shank being smoothly drilled and the outersurfaces of the outer wires of the conductor strand being cold drawn tothe usual smooth finish. Consequently, compression of the tubular shank{onto the end of the conductor strand 4 cannot produce a joint havin atensile strength equaling the tensile strength of the conductor strand.This lack of strength resuits both from the ability of the outer wiresof the strand to slide relative vthe inside of the shank, and from thetendency of the inner wires of the strand to slide relative the outerwires of the strand. Furthermore, the inside of the tubular shank andthe outside of the end of the conductor strand become coated with oxide,grease and other contamination, prior to insertion of the strand intothe shank in the quantity production of bonds, and it follows that whenthe joint is ultimately made it does not possess as high electricalconductivity as is desirable.

The foregoing discussion is likewise applicable to the manufacture ofbonds of the type shown by Figures 4 through 8. The terminal of thisbond has a head 8, a stud 'l and a tubular shank 8 in which the end ofthe conductor strand 9 is inserted. Since this bond must be made with ashorter shank 8 to permit its use in its intended manner, a hole isdrilled through the originally solid shank and into the head 8, thelatter initially being suiilciently large to accommodate the drilling ofa hole of the diameter of the conductor strand, as shown by Figure 4.After the end oi. the strand is inserted, the head of the bond is coldcompressed so as to flatten it andthe eonductor strand to the form shownby Figures 5 through 8, the tubular shank being flattened into arectangular form along with the portion of the strand inside it, thisresulting in a; shape such as shown by Figure I, while the.head andconductor are greatly fanned out, as shown by Figures 6 and B.

The terminals of electric power bonds of the two types illustrated, ineach instance, are forged from pure electrolytic copper. Although theshank, which is originally solid, can be drilled satisfactorily in thequantity production of the bonds, it is impossible to satisfactorilyapply machining operations to roughen the inside of the smoothly drilledhole into which the conductor strand end is inserted. This is becausepure electrolytic copper is a material which cannot satisfactorily bemachined at high speeds. In addition, it is impossible in the quantityproduction of bonds to machine the outer surfaces of the outer wires ofthe conductor strand, this following from the inherent nature ofstranded assemblies.

According to the present invention, the smooth inside of the tubularshank of the terminal and the smooth outer surfaces of the outer wiresof the conductor strand are abraded to roughness by a suitable abrasivemeans. In the actual commercial production of bonds the abrasive meansconstitutes wire brushes.

In the drawing, Figure 9 shows a rotary chuck li turning a sleeve i2clamped about a length of wire rope having its ends flared as at I; toprovide a stiff rotary brush. The sleeve I! is positioned slightly of!center so as to cause the rotary brush to wobble. The tubular shank 8 ofthe terminal of the bond shown by Figures 1 and 2 is shown as beingmanually worked over this brush I! while being turned so as tothoroughly abrade its inside to a slight degree of roughness. Quantityproduction of rail bon'ds has been practiced by this procedure. Figureof the drawing shows the end of the conductor strand 4 being abraded toroughness by a rotary wire brush ll of the type used for cleaningpurposes in machine shops. Here again, the part is held manually andturned during the abrading operation. Substantially the same procedureis followed in the manufacture of the bond of the type shown by Figure4.

As shown by the drawing, the result of the above described abrading isto provide the interengaging surfaces of the inside of the shank of theterminal and the outsides of the outer wires of the conductor, withcircumferential grooves abraded lntothese surfaces. This results fromthe turning of the surfaces circumferentially respecting the rotary wirebrushes in the manner described. These abraded surfaces eliminate thenecessity for using interposed material in the nature oi hard granulesor the like, this expedient being suggested in the case or prior artattempts to eilect a high-strength joint but being objectionable in thatthe Joint then does not have high electrical conductivity. This followsfrom the fact that the conductivity of such granules cannot possiblyapproach that of the electrolytic copper shank.

The above described brushing, in addition to slightly roughening theinter-engaging surfaces of the terminal shank and conductor strand, alsothoroughly cleanse them of the oxide, grease, etc., with which theseinterengaging surfaces become contaminated when the parts are handled asthey must be in the quantity production of rail bonds. Immediately afterthe brushing operation, the joint is assembled. there being no time forthe formation of further oxide or chance for the parts becoming dirty. I

Anchorage of the inner wires of the conductor strand respecting theouter wires may be eiiected by Joining the ends of all of the wires oithe conductor to a common mass of molten metal which, when solidified.causes the end of the conductor strand to be a unit in so far as itsvarious wires are concerned. This may be done eitherbyweldingasteelbuttontotheends ofallthewires,byhrasingorbyfusingthewireendstogether. In any event the idea isto join the endsofallthewiresbymeansciacommcnmass ofmetal.InFigure2thismassofmetalis shown at I These steps having been periermed.the end of theccnductorstrandisinsertcdinthembular shank and the lattercold compressed. Usually thisisdoneinsuchamannerastomaintain thecylindrical shape of the shank and of the strand within. However.according to the presentinventiontheshankiscompresscdiromits mouth,from'which the conductor strand extends, from its uncompressed diameterto gradually progressingsmalierdiameterstoapointspacedirom itsmouthwhere it is compressed to a diameter cdmpressing the eonductor'strandwithin to a diameter appreciably smaller than the comressed diameter ofthe conductor strand. x shank being then compressed to eflect graduacaacse increasing sizes from this point in a direction toward the endof the conductor strand: Prefer ably, this compression is eifected bytwo dies having suitable contours for eii'ecting the varying degrees ofcompresslon when brought together.

In Figure 2, the mouth of the conductor is shown at 8" and the point ofmaximum compr slon is shown at I, the increase in diameter beyond thepoint 3"- providing a socket in which the end of the conductor strandworks as a wedge. In Figures 5 through 8 the mouth of the shank isindicated at I and the point of smallest diameter at I". it being notedthat in this instance the fanned portion of the strand from the point Ito the extreme end of the strand is the portion providing the wedgeeffect. Since this extreme flattening of the strand i fixes all or mostof the wires against movement, the ends or the wires need notnecessarily be Joined, no mass of metal being shown because of this.

In the case of either bond the mouth 8 or I does not compress theconductor strand to any great degree, compression being graduallyapplied from the mouth to the point of smallest diameter. The contour ofthe inside of the shank, in each instance, is smoothly curving with nosharp bends, particularly between the point of smallest diameter and themouth of the shank. Because of this construction, vibration between theterminal and strand cannot cause the concentration of vibratory stresseswhich results when the shank is compressed cylindrically, the stressesbeing gradually transmitted between the interengaging surfaces andterminal shank.

I claim:

1. A method of making a joint of high electrical conductivity andstrength between a tubular part made of electrolytic copper and aconductor made of intertwistedi copper wires including working theinside of t e part with a wire brush to remove all conta nation androughen it. working the outer surfaces oi the outer wires of theconductor to remove all contamination and roughen these surfaces,inserting the conductor in the part so the abraded surfaces of theconductor and of the part directly intercontact and are free frominterposed material, and cold compressing the part onto the conductor.said method including interconnecting the ends of all oi the wires orthe conductor with molten metal prior to insertion of the conductor inthe part.

2. A method of making a joint or high electrical conductivity andstrength between a tubular art made of electrolytic copper and aconductor made of intertwistcd copper wires, including working theinside or the part with a wire brush to remove all contamination and touhen it,

working the outer surfaces of the outer wires of the conductor to removeall contamination and roughen these surfaces. inserting the conductor inthe part so the abraded surfaces of the conductor and of the partdirectly intercontact and are free from interposed material, and coldcompressin the part onto the conductor, said method includinginterconncctingtheends oiallof hewli'es of the conductor with moltenmetal prior to insertionoi'theconductorinthcpartandccmressing the partirom its mouth from which the conductor extends from its uncompresseddiameter to gradually progressing smaller diameters toa point spacedfrom .its mouth where it is compressed to a diameter compressing theconductor to a diameter appreciably smaller than the uncompresseddiameter of the conductor.

' surfaces or the inside oi. the part and 3. A joint or hish electricalconductivity and strenzth, comprisins a tubular pert made ofelectrolytic copper cold compressed onto a conductor made of strandedcopper wires, the interchanging oi the outer wires oi the conductorbeing abraded to roughness and free from interposed material, the ends0! all the wires of the conductor being interconnected by a solid metalmass preventing slippage oi the inner wires and the part beingcompressed from its mouth from which the conductor extends from itsuncompressed diameter to grad ually progressing smaller diameters to apoint spaced from its mouth where it is compressed to a diametercompressing the conductor to a diameter appreciably smaller than theuncompressed diameter of the conductor.

4. A method of making a joint of high electrical conductivity andstrength between a tubular part made of electrolytic copper and a.condoctor made of stranded copper wires, the method comprising abradingcircumferential grooves into the surfaces of the inside 0! the part andthe cutsides oi the outer wires of the conductor by sesame contactingthese surfaces with a rotary wire brush while turning the surfacecircumferentially respecting the brush, inserting the conductor insidethe tubular part so that the abraded surfaces of the conductor and orthe part directly intercontact and cold compressing the part onto theconductor to complete the joint.

5. A method of making a. joint of high electrical conductivity andstrength between a tubular part made of electrolytic copper and aconductor made of stranded copper wires, the method comprisinginterjoining the ends of all the wires of said conductor by a commonmass of fused metal, abrading circumferential grooves into the surfacesof the inside of the part and the outsides o! the outer wires 01 theconductor by contacting these surfaces with a rotary wire brush whileturning the surface circumferentially respecting the brush, insertingthe conductor inside the tubular part so that the abraded surfaces oithe conductor and of the part directly intercontact and cold compressingthe part onto the conductor to complete the joint.

ERNEST J. SABOL.

